Francis M. Balfour

“ The embryo was hardened in a mixture of chromic acid and osmic acid.
The section shews the commissures which dorsally unite the posterior roots, and also the junction of the anterior and posterior roots. The commissures are unfortunately not represented in the figure with great accuracy; their outlines are in nature perfectly regular, and not, as in the figure, notched at the junctions of the cells composing them. Their cells are apparently more or less completely fused, and certainly not nearly so clearly marked as in the figure. ”

“ Fig. 3. Section through the head of a Pristiurus embryo during stage G. It shews (1) the fifth nerve (v.) arising as an outgrowth from the dorsal summit of the brain. (2) The optic vesicles not yet constricted off from the fore-brain.
Figs. 4a and 4b. Two sections through the head of a Pristiurus embryo of stage I. They shew (1) the appearance of the seventh nerve. (2) The portion of the body-cavity belonging to the first and second visceral arches. (3) The commencing thickening of epiblast to form the auditory involution. ”

“ The sections shew that the oviduct arises as a thickening on the under surface of the segmental duct into which at the utmost a very narrow prolongation of the lumen of the segmental duct is carried. The small size of the lumen of the Wolffian duct in the foremost section is due to the section passing through nearly its anterior blind extremity.
Fig. 2. Section close to the junction of the Wolffian duct and oviduct in a female embryo of Scyllium canicula belonging to stage N. Zeiss B, ocul. 2. ”

“ Fig. 10. Section through superficial part of the ovary of an embryo, shewing the pseudo-epithelium; the cells of which are provided with tails prolonged into the general tissue of the ovary. At f.e. is seen a surface view of the follicular epithelium of an ovum. Zeiss C, ocul. 2. Picric acid.
Fig. 11. Section through part of an ovary of Scyllium canicula of stage Q, with three primitive ova, the most superficial one containing a modified nucleus.
Fig. 12. Section through part of an ovary of an example of Scyllium canicula, 8 cm. long. ”

“ Fig. 32. Section through the skin of Peripatus capensis; it shews the secondary papillæ covered with minute spinous tubercles and the relation of the epidermis to them. (The cuticle in the process of cutting has been torn away from the subjacent cells.) The cells of the epidermis are provided with large oval nuclei, and there is a deposit of pigment in the outer ends of the cells. The granules in the protoplasm of the inner ends of the cells are arranged in lines, so as to give a streaked appearance. ”

“ Internal opening of nephridium into the body-cavity (lateral compartment) . s. Vesicle of segmental organ. s1. Portion of segmental organ of 4th and 5th legs, corresponding to vesicle of the other nephridia. s.c.1. First or external portion of coiled tube of nephridium, lined by columnar epithelium with small nuclei; the cells project for very different distances, giving the inner boundary of this region a ragged appearance. ”

“ The proximal part of the duodenum and the terminal part of the intestine are represented as cut open, the former to shew the pyloric valve and the apertures of the pyloric cæca and bile duct, and the latter to shew the spiral valve. ”

“ The commissures stain very deeply with the mixture of osmic and chromic acid, and form one of the most conspicuous features in successful longitudinal sections of embryos so hardened. In sections hardened with chromic acid only they cannot be seen with the same facility.
sp.c. spinal cord. gr. grey matter. w. white matter. ar. anterior root. pr. posterior root. x. commissure uniting the posterior roots. ”

“ Fig. 15. Section through the point of junction of the salivary ducts with the median oral diverticulum.
Fig. 16. Section behind the pharynx through the œsophagus.
b.c. Body-cavity. C. Cutis. c.b.c. Central compartment of body-cavity. c.g. Supra-œsophageal ganglia. c.m. Layer of circular muscles. co. Commissure between ventral nerve-cords. co. 2. Second commissure between the ventral nerve-cords. co1. 2. Mass of cells developed on second commissure (probably sensory) . c.s.d. Common duct for the two salivary glands. d.l.m. Dorsal longitudinal muscles of pharynx. ”

“ Crural gland. h. Cells in lateral compartment of body-cavity. o.f.g. Orifice of accessory foot gland. o.s. Opening of segmental organ. P. Three spinous pads on ventral surface of foot. pr. Prostate. R.M. Retractor muscle of claw. s. Vesicle of nephridium. s.c.i. Region No. 1 of coiled part of nephridium. sl.g. Tubule of slime gland. s.o.t. Terminal portion of nephridium. st. Stomach. st.e. Epithelium of stomach. v.c. Ventral nerve-cord. v.d. Vas deferens.
Fig. 21. Longitudinal vertical section through the supra-œsophageal ganglion and œsophageal commissures of Peripatus capensis. ”